Such a reflector lamp is known from European Patent No. EP-0 422 936 A2.
The known lamp has a neck-shaped insulator body with a wide portion which surrounds the neck-shaped portion over the major part of the latter's length, and a narrow portion which is accommodated in the lamp cap.
In the known lamp, the insulator body has the object of preventing light from radiating from the neck-shaped portion to the exterior as a result of an imperfect coating of that portion with a mirroring layer.
A disadvantage of the known lamp is that the insulator body must be fastened to the reflector body with a first adhesive compound. It is apparently necessary for this to provide the insulator body with a projection and the reflector body with a groove cooperating therewith in order to give the fastening the required torsional strength. A second adhesive compound is necessary for fastening the lamp cap to the insulator body.
The projection and groove may at the same time form the stop for limiting the depth to which the neck-shaped portion enters the insulator body. The reflector body, which is externally conical, and the insulator body, which is internally conical, however, by their very shape and dimensions already constitute a depth stop, i.e. a stop in the direction of the optical axis.
The known reflector lamp complies with the ANSI standard for the dimensions of the lamp contours. This standard envisages inter alia to prevent that a lamp can be screwed tightly into a lampholder without the lamp cap thereby making electrical contact with the bottom of the lampholder. The known lamp for this purpose has a width in the immediate vicinity of the lamp cap which corresponds to the greatest width of the lamp cap.
Another disadvantage of the known lamp is that the lamp does not comply with the IEC standard as regards its contours. This standard is in contradiction to the ANSI standard and indeed requires the width of the lamp in the immediate vicinity of the lamp cap to be greater than the width of the lamp cap. The object of this standard is to avoid that the lamp cap can be touched when the lamp is inserted into a lampholder.